/Engine/Source/Runtime/Core/Public/Misc/MapErrors.h
{Actor} is obsolete and must be removed!: This warning is caused when there is an instance of a actor in a level that has been marked deprecated. This is usually because a actor was marked deprecated after the level was created, but the map was never updated. This can be fixed by simply deleting the actor.
static [FLazyName](API\Runtime\Core\UObject\FLazyName) ActorIsObselete;